The main growing season is upon us, which means the days are getting longer, the sun is peeking through more often, and that familiar itch to get your hands dirty in the garden is starting to blossom. March in the UK marks the turning point, where thoughts of a flourishing vegetable patch are at the forefront of our minds.

Our garden guide will navigate you through the exciting options for March vegetable planting, whether you're a seasoned grower or just starting your edible journey. We’ll also look at how the changeable weather in March can impact your veg growth and how to water for the best results!

Whether you have a greenhouse, a sheltered outdoor vegetable garden, or are limited to indoor sowing for now, let’s have a look at which veg seeds you can start sowing in the UK during March.

Peas

Peas do not germinate in cold weather conditions, which is why it’s a good idea to wait until the weather starts to warm up before sowing pea seeds. These little green veggies are an easy crop to grow and are perfect for beginners- plus they take up very little ground space. Starting them off indoors is usually your best bet, but as soon as seedlings have emerged, you can transplant them in a sunny spot in your garden or vegetable plot. Don’t forget to space the seedlings out so they have room to grow and remember to provide them with canes or netting for support as they grow tall – the perfect vegetable to plant in March and enjoy later in the year!

Early Brassicas

Lucky for the summer cabbage and cauliflower lovers, early brassica is an amazing vegetable to plant in March in your greenhouse. It’s important to make sure the soil is in the right condition to help these vegetables grow. Wet and cold soil is what we want to avoid, so you might want to find a weather-responsive irrigation system to ensure your brassicas are getting the perfect amount of water every time!

See more tips on how to get your produce to flourish on our blog.

Leeks

Packed with vitamins and high in fibre, leeks are highly nutritious. March is the peak sowing window in the UK for these delicious vegetables, offering the perfect opportunity to cultivate these for autumn and winter harvests. While they can withstand cooler temperatures if you want to make the most of your garden over winter, we recommend waiting until the soil warms slightly (around 7°C). Leeks love a good drink, so you’ll need to keep the soil consistently moist but not waterlogged. With a little care and attention, you'll be rewarded with tender, flavourful leeks that add a delicious touch to soups, stews, and roasted dishes throughout the colder months.

Onions and Shallots

March is a great time to get ahead and get those onions and shallots planted. A longer growing season has a huge impact on the size of these versatile vegetables. Though onions can stand colder temperatures, planting them in a greenhouse is a great way to get them started. Shallots, however, thrive in warmer conditions with drier and warmer soil. 

Beetroot

These veggies are packed in fibre and antioxidants. Not only are they great in the kitchen, but they’re even better in the garden and beetroots are a great plant to sow in March alongside other vegetables.

There are a number of amazing varieties of beetroot in the UK, and the edible leaves can be delicious and colourful addition to summer salads!

Broad Beans

If you haven’t sown any broad beans yet, it isn’t too late! You can opt for successional sowings to get a longer season of small tender beans. Our resident gardener, George, loves to grow plenty of broad beans; not only are they a kitchen staple but you can store them in the freezer and use them for a huge range of dishes throughout the year. What’s more to love than delicious, nutritious food straight from your garden?

Parsnips

While parsnips tolerate cooler temperatures than many vegetables, waiting until the soil warms slightly in March (ideally around 5°C) helps ensure good germination and avoids the risk of frost damage to delicate seedlings. We recommend opting for a sunny spot to plant these winter veggies and sow directly where they'll grow. Parsnips are renowned for slow germination, but hang in there as they develop their sweet, nutty flavour throughout their long growing season.

Carrots

Early varieties of carrots can be sown in March and sometimes as early as February. This deliciously nutritious vegetable is straightforward to grow and if you decide to make regular sowings, you’re guaranteed throughout the year. You can sow your seeds directly outdoors in shallow drills about 1cm deep or start seeds indoors in trays or modules for transplanting later.

Radish

Radishes come in an array of shapes, sizes and colours. This month, you can start to think about which type you’d like to plant throughout the year. The most popular type are salad radishes and March the perfect time to plant them. These quick-growing vegetables thrive in the cool but warming temperatures of spring, offering a spicy burst of flavour within just a few weeks. These are quick to germinate, with the process only taking between 7-10 days. Choose a sunny spot outdoors and sow radish seeds directly in shallow drills about 1cm deep. You don’t even need to worry about thinning them later – these little guys grow fast!

Herbs

While almost any herb can be grown in a greenhouse, we recommend utilising greenhouse space to grow the herbs that can be too tender for a garden. George suggests sowing parsley in the greenhouse as the germination is slow and erratic, and this herb needs time to flourish.

Planting Conditions in March

March is the penultimate month of planning, prepping and perfecting in order to enjoy the fruits of our labour throughout the rest of the year! This time of the year can be a bit of a mixed bag in the UK, while the average temperatures start to creep up - hovering around 7-10°C, unexpected frosts and windy days are still common.

It’s crucial for us to be strategic with our planting choices as the weather starts to change, taking into consideration the options available to us.

Optimal Watering in Changeable Weather

With Irrigatia’s weather-responsive watering systems, you don’t need to worry about watering the vegetables you plant in March, as they’ll be receiving the right amount of water regardless of the temperamental spring weather.

The SMART irrigation system detects changes in the weather and conditions to provide plants with optimal growing conditions for heights of up to 5 metres, ensuring all of your greenhouse plants can benefit from automatic watering, whether you’re sowing seeds for a regular supply or successional sowing.

Check out our C12L or C24L for smaller gardens, or our DIY SOL-C60, C120 or C180 systems to create a bespoke watering solution for a larger space!

We hope you’re feeling inspired to start sowing your vegetable seeds this March! For more greenhouse tips and gardening advice check out our blog and don’t forget to follow our Instagram and Facebook accounts to keep up to date with the latest projects in the Irrigatia Garden. If you’re interested in perfecting your watering system, please get in touch with our expert team for more information.